There is no admission that the background art disclosed in this section legally constitutes prior art.
Over the past twenty years, homogeneous and heterogeneous catalysts comprised of single-site molecular complexes (typically of titanium, zirconium, or other early transition metals, as well as nickel, palladium, and platinum) have replaced traditional Ziegler-Natta catalysts for the polymerization of alkenes. Unlike conventional catalysts, these new catalysts allow precise and previously unprecedented control over polymer properties, including tacticity and molecular weight. The organic compounds (ligands) that bind to the metal are highly desirable for tailoring the activity and selectivity of the resulting catalysts. Thus, new ligands for single-site catalysts are of considerable commercial interest for a variety of applications.
One particular class of ligands is that which favors formation of constrained geometry catalysts (CGCs). These ligands are typically comprised of a cyclopentadienyl moiety with one or more substituents capable of binding to a metal. These ligands are typically monoanionic or dianionic. What is needed is a class of previously unknown ligands with potential applications for CGCs for metathesis reactions, hydroamination of alkenes, and oligomerization and polymerization of alkenes, epoxides, cyclic ethers, lactones, and other monomers. These objectives and others are met by the present invention.